Is this workout the secret to faster muscle growth?

By Alistair Gardiner
Published March 11, 2021

Key Takeaways

Are you working out regularly? If not, you probably should be. Whether it’s strength training, running, or high intensity interval training, working out is beneficial to cardiovascular function, brain health, and many other aspects of your health.

But what if you have, or have had, a condition that makes it difficult to endure intense workouts, or you’re looking to get those gains while reducing your risk of injury? Blood flow restriction (BFR) training may be the answer. 

Here’s your introduction to BFR, including the science on why it works, and how to do it safely.

What is blood flow restriction training?

BFR is a training method in which tourniquet cuffs are used on the upper or lower limbs to partially restrict blood flow to the muscles. According to a review published in the American Journal of Sports Medicine, during BFR training, arterial inflow is somewhat restricted and venous outflow is fully restricted. 

This results in an inadequate supply of oxygen, known as hypoxia, within muscle tissue. As explained by the authors of an article published in Strength and Conditioning Journal, this effectively challenges local energy metabolism and reduces the time required to hit your aerobic or strength limits. When applied in weight training, BFR reduces the amount of weight required to hit your one-rep max.

According to a review in Frontiers in Physiology, BFR originated in Japan in the 1960s, when it was discovered by researcher Dr. Yoshiaki Sato. Sato called it “Kaatsu” training, which roughly translates to “training with added pressure.”

Now, however, it’s practiced all over the world—and not only by athletes looking to get maximal muscle growth without putting too much stress on their joints, but also by those who are prescribed physical therapy but may be too frail to lift heavier loads.

Does blood flow restriction training work?

According to the aforementioned in the American Journal of Sports Medicine, BFR provides several athletic benefits.

The authors of the review analyzed 10 studies, all of which were randomized with control groups, that involved applying BFR to athletes’ resistance training workouts. Seven of the studies indicated BFR induced a “significant increase in strength” compared with the control group. Half of the studies found that BFR resulted in “significant increases in muscle size” and roughly three-quarters found that “significant improvements in sport-specific measurements” were associated with BFR.

The authors of the review concluded that evidence supports the notion that BFR can lead to improvements in strength, muscle size, and markers of sports performances in athletes. 

While that review focused on athletes, another review published in Scandinavian Journal of Medicine & Science in Sports, included studies on a wider range of individuals. Its authors pooled data from 16 studies that included more than 300 healthy and habitually active individuals aged 20-80. They concluded that low-load BFR training is equally effective in producing gains compared with heavy-load strength training. 

How to practice BFR safely

According to a 2018 review, published in Techniques in Orthopaedics, the data indicated that BFR training is a safe alternative to traditional forms of exercise for healthy individuals. The authors did, however, list a number of conditions that present possible contraindications, including coronary heart disease, unstable hypertension, cardiopulmonary conditions, musculoskeletal injuries, clotting disorders, and others.

While the review does note several possible adverse effects of BFR training (including numbness, dizziness and muscle damage), available literature suggests that these are either temporary events or minor risks, no greater than with traditional forms of exercise. The authors do mention that seeking the aid of a practitioner is recommended, particularly when it comes to determining things like tourniquet  cuff pressure.

Similarly, the authors of the Frontiers in Physiology review, looked at the safety of BFR training from a number of health and safety angles and concluded that some practitioners may not be informed on how best to implement BFR training. As such, they included some basic guidelines on BFR resistance training and BFR aerobic training.

For BFR-resistance training, the authors advise working out two to three times a week, lifting only 20-40% the weight of your 1-rep-max. Your restriction time should be 5-10 minutes per exercise and you should be aiming for 2-four sets. The pressure of the cuffs should be at around 40-80% (where 100% marks the point where blood flow ceases).

For BFR-aerobic training, the authors advise working out two to three times a week, with less than 50% of your normal intensity. Again, the pressure on your cuffs should be no more than 40-80%.

If you’re looking for gains that don’t beat up your body, blood flow restriction training may be worth considering. But make sure you consult a physical therapist or BFR instructor before you start, particularly if you have pre-existing conditions, just to be safe. While BFR is becoming more mainstream (with tourniquet cuffs available at various sports stores) and there are a number of tutorials online, speaking with someone who has professional experience will ensure you don’t use too much pressure or push yourself too hard.

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